4. Open the Activity Monitor app and type "cfprefsd" in the search box at the upper right.

5. Selected the cfprefsd process with your username in the User column and click the force quit button in the top left and click the Quit button in the alert dialog that comes up.

6. Launch PS, try to show Design Library, then quit after it closes.

7. Share the new log file

You can later return to the default log level using step #3 with a value of "1". Step #4 forces the system to read the new value rather than continue using a cached value so you can also do that, or not - it will eventually take effect regardless.

I'm not sure why that would happen. Could be errant quotes of some sort in what you've pasted, or not specifying the value, or probably a variety of other things. Try just typing it instead of using copy/paste. Everything between (but not including) the quotes:

"defaults write com.adobe.CSXS.5.plist LogLevel 6"

If that doesn't work then we may need to do a screen share to help sort it out.

Unfortunately that doesn't provide any more clues. Please locate the cef_debug.log file next:

/Users//Library/Logs/CSXS/cef_debug.log

Try deleting it, launching PS, trying to show Libraries, quitting PS, and then providing us that file to see if it will tell us something useful.

Also:
- Does the Welcome screen come up and show content when you first launch Photoshop (or show successfully if you choose Help > Welcome...)?
- Does File > Extract Assets work?
- Does File > Share on Behance work?